Such circuit breakers are known which enable currents of various magnitudes to be interrupted: the action of a mechanical blast is sufficient for small amplitude currents; the action of the thermal blast has progressively more effect with increasing amplitude of the current to be interrupted.
One aim of the present invention is to provide a gas blast circuit breaker using the mechanical and the thermal effects in which the energy required for the mechanical blast is minimal for as an effective a result as possible.
Another aim of the invention is to provide a circuit breaker in which the heat generated by the arc is diffused very quickly in the gas in order to avoid hot spots, while retaining a small gas volume in order to enable high pressure to be created.